fuel pump keeps blowing fuses

[markh1]

For some unknown reason my fuel pump keeps blowing fuses.

I was on the way to the MOT this pm and about 20 minutes into the journey the car cut out. I tried replacing the fuse but it blew it straight away.

I know the fuel pump circuit is on the same one as the oxygen sensors so Matt at Sebring thought it might be the wires for them shorting out but they seem fine.

Has anyone got any helpful suggestions??

Thanks,
Mark

[markh1]

Right solved the fuel pump fuse problem! Where I had replaced the fuel lines the metal part of the fuel line was touching one of the terminals on the fuel pump and shorting it out. The fuel pump now works....

However! Next problem! The engine won't fire! I have tried cycling the pump so it pushes fuel through - done this a dozen or so time but to no avail!

Oh the trials and tribulations of cerbera ownership!!!

[high52kojak]

So are you sure your fuel pump now works??

[markh1]

well I can hear it wizzing like normal but does that not necessarily mean it is working?

Edited to add...

I have taken the pipe that goes from the pump to the fuel cooler and run the pump fuel is coming out but not really at any pressure. Is this right or should it be squirting out with some force?

Edited by markh1 on Tuesday 23 March 21:06

[Nickccc]

Undo the fuel pipe at the pass side inlet on the ac cooler, put it into a pot
then turn on ignition, see if any fuel is pumped through the line.
Easier to get some one to turn ignition on if you can.

[markh1]

Hi Nick, I have just edited my post above to say I have tried that. Fuel is coming out but not any great pressure.

I have had enough of messing around with it tonight so will try again tomorrow.

[Nickccc]

I know the pressure at the rail should be just over 2 bar, maybe someone knows how many
l/PH the fuel pump is. Run it for a minute measure output and multiply by 60 should tell you if
your pump is flowing enough. Then again maybe it'll be in a better mood tommorrow and start
straight away, you know what Cerbs are like.

Just thought probably best to start at 15 seconds, as it could pump too much through.

Edited by Nickccc on Tuesday 23 March 21:33

[markh1]

Yeah I will try that thanks.

Is there an easy way to tell whether there is actually a spark?

[julian64]

Yep you can buy a plug that goes on an HT lead, and tells you. I think halfrauds sell them. The advantage of them is that they can tell you something about whether a spark is forming and more importantly how big

[markh1]

Great I will take a trip to halfords tonight, thanks Julian.

edited to add...

Will the 'continuity test function' on this do the same job?

http://www.robertdyas.co.uk/P~124458~Draper+Batter...

Edited by markh1 on Wednesday 24th March 08:45

[julian64]

markh1 said:

Great I will take a trip to halfords tonight, thanks Julian.

edited to add...

Will the 'continuity test function' on this do the same job?

http://www.robertdyas.co.uk/P~124458~Draper+Batter...

Edited by markh1 on Wednesday 24th March 08:45

Nope thats a waste. For £2.99 at maplins you can get a meter far better than that for general car use.

http://cpc.farnell.com/_/dt830d/digital-multimeter...


The problem is that HT leads are high voltage so a normal multimeter won't do.

I use a simple lead with a crocodile clip at the end, and attach it to an ocilloscope.

think this

http://books.google.co.uk/books?id=otgDAAAAMBAJ&am...

[markh1]

Ok there is a Maplins not far from my office, does not look like they sell anything to test the spark.

I have just spoken to ridds on the phone and he reckons from what I have described, that the pump is not flowing enough fuel (he thinks it should be flowing about 3 litres a minute) so could be a new fuel pump is needed.

I have found this...

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&am...

When I think about it the only problem seems to be around the pump - the engine was sparking and running perfectly well before.

[julian64]

I have to say I think he's right. Last time I took the pipe off my fuel pump it literally soaked me trying to put my finger over the end.

[JensenA]

Here's the spec for the standard Bosch one Mark. I guess if it meets this spec it will be fine.

http://tvrcerbera.co.uk/Gallery/displayimage.php?p...

[markh1]

Glad you have said that Julian, you have added weight to Ridds and my suspicions.

Alan that is very helpful. They are the same spec fittings wise but are more powerful. This is the one I have ordered...

http://cgi.ebay.co.uk/TVR-TUSCAN-CERBERA-GRIFFITH-...

It will arrive tomorrow but wont get a chance to fit until Friday so will let you all know the result then!

Thanks for all the help! PH collective wisdom saves the day again!

Edited by markh1 on Wednesday 24th March 11:27

[jammy_basturd]

Whatever happened to just taking the spark plug out, putting it back in the HT lead and holding it (with thick insulated gloves) against the engine block?!

You do need an assistant to either do the holding or the engine firing.

Edited by jammy_basturd on Wednesday 24th March 11:50

[julian64]

jammy_basturd said:

Whatever happened to just taking the spark plug out, putting it back in the HT lead and holding it (with thick insulated gloves) against the engine block?!

You do need an assistant to either do the holding or the engine firing.

Edited by jammy_basturd on Wednesday 24th March 11:50

Real men don't use gloves . As long as the route through the engine to earth is better than the route though you to the floor by a factor of about ten to one you shouldn't get a shock.

But the oscilloscope shows you timing, power/brightness of each spark, plug gap and insulation performance of the plup or MEP in the cylinder all compared with its neighbours.

All without the need to be a gynaecologist in the case of a cerb.

[markh1]

Just fitted the new pump and it fired into life!!

Thanks again for your help chaps! Invaluable as always!!